You can set a lifespan to eliminate nParticle from the scene when they reach the specified age. Lifespan is typically set on emitted particles. For example, you can use lifespan to fade out emitted smoke or fire. You can set the lifespan for all the particles or on a per-particle basis. By default, nParticles are set to live for the duration of the simulation. See nParticle Lifespan attributes. See also How particle Lifespan is calculated.
For information about setting per-particle Lifespan using an expression, see Work with lifespan.
Setting per-object lifespan assigns the same lifespan to all particles in the particle object. You can make particles live forever or make all particles die at the same age.
To make particles live forever
To make particles die at the same age
The Lifespan value is the number of seconds that the particle object exists after it is created. A particle object you create with the nParticle Tool is considered to be created immediately at the beginning of the first frame of the scene. An emitter particle is created when it is emitted. The default value of 1 makes the particle object disappear after one second.
Setting per-particle lifespan assigns different lifespans to each particle in the particle object. You can make particles die at random ages, assign a lifespan to individual particles, or use an expression to control the lifespan.
To make particles die at random ages
The lifespan is uniformly distributed with Lifespan as the mean and Lifespan Random as the width of the distribution.
For example, if Lifespan is 3 and Lifespan Random is 2, then each particle will have a lifespan between 2 and 4.
The random number stream for Random range lifespan mode is maintained inside the particle object and is automatically re-seeded when you rewind. You do not have to reseed it yourself.
Normally, you don’t need to change this value. If you want two identical looking particle objects, you can set this value to match the other particle object’s General Seed value.
To control lifespan of individual particles
See Set particle attributes with the Component Editor for more information on using the Component Editor.
To use expressions to control lifespan
Note that you cannot key this attribute or other per particle attributes.